[Help-gsl] hi :-) \o/ I've some problem with eigensystem

[Giuseppe Marco Randazzo]

Hi all! :) first of all i must congratulate with all for this project. Now i 
come to the point. I've read the documentation about the eigensystem and i've 
understood (more or less) how it works. :) I took the example code for a 
computation of eigenvalue end eigenvector for a matrix square of order 4, and 
i've modify the data vector to two and i've changed more stuff signed with 4 
to 2 because is a matrix of order two. So the point of question is this: the 
results that i get have the right values but the signs wrong.  Here i write my 
example and the results that i've to get:

double data[] = { 0.616556, 0.615444,
                  0.615444, 0.716556};


The right results of eigen value and eigen vector:

eigenvalue= ( 0.04908339 )
            ( 1.28402771 )


eigenvectors = ( -0.735179  -0.677873 )
               ( 0.677873    -0.735179 )
  

The value which i took with the sample code instead are this:

eigenvalue = 0.0490843
eigenvector = 
0.735179
-0.677873
eigenvalue = 1.28403
eigenvector = 
0.677873
0.735179


So, the eigenvalue are ok, also the values of eigenvectors, but the signs are 
not correct :|

The sample code which i've used come from here >> 

http://www.gnu.org/software/gsl/manual/html_node/Eigenvalue-and-Eigenvector-
Examples.html

and is the first example of the page (15.8 Examples)

Now, i do not know where i' m wrong with the code, and if i've not understood 
the right mode the gsl library, or simply if this could be a bug? :-)


Thanks. 

zeld :-)